I agree with Bill above. The spots are too well distributed and uniform in size to be a fungus.
My experience is fungus is more patchy and larger and uneven, like a spider web.
I would just use the binoculars, it may not get any worse, and yes it can be cleaned up by a
qualified tech. Nikon should cover this under their warranty, I would check there first.
I am thinking of sending the pics to Nikon to see if they can shed some light on this but as the bins are out of their 10 year warranty it would most likely be very costly to get them fixed. At least they are now just a back up pair.